This invention relates to an improved furnace useful for heating a building, and is more particularly concerned with a furnace capable of burning both fluid or solid fuels for the purpose of heating air which is circulated to the rooms of a building.
Many residential dwellings are equipped with fireplaces designed for the burning of wood in the form of logs. In such fireplaces, the fire creates an upward draft causing considerable amounts of air to be taken from the building and transported up the flue or chimney and out of the building. The only heat provided by the burning wood is of a radiative nature, and it generally does not compensate for the amount of heat removed from the building in the form of air exhausted through the chimney. Also, whereas the radiative heat will generally affect only the room in which the fireplace is located, the removal of air from the building will cause other rooms to become colder because of the influx of colder air from outside the building. Most such fireplaces are in effect intended primarily as decor, particularly to many who find the burning of logs to be an aethetically pleasing sight.
For actual heating purposes, most residential homes are equipped with specially designed furnaces wherein a liquid fuel such as gas or oil may be continuously and controllably fed to a burner wherein it heats the walls of a combustion compartment. Heat is transferred from the hot outer walls of the compartment to a circulating stream of air which is conducted to the various rooms of the building.
There are numerous disclosures of improved fireplaces wherein heat generated from the burning of wood or coal is caused to heat walls of a chamber which transfers the heat to a circulating stream of air in a manner similar to that employed with oil and gas operated furnaces. Specific examples of such systems may be found in the following U.S. Pat. Nos. 234,921; 695,840; 1,656,326; 2,154,939; 1,505,407; 2,453,954; 2,791,213; 2,172,356; 2,283,790 and 3,981,292.
Although fireplace structures are known having the capability of burning fluid fuels such as gas in addition to wooden logs, the efficiency of utilization of such fluid fuels is generally poor, and no provision is made for the concerted utilization of two different fuels to provide a continuous and controllable amount of heat. In the interest of reducing manufacturing cost and facilitating maintenance, simplification of the construction of such dual mode furnaces is desirable.
Since wooden logs are generally stored outside the building heated by the furnace, the use of wood as a fuel generally necessitates frequent trips outside the building and the carrying of logs through the building. Not only does this admit colder outside air to the building, but it incurrs the risk of introducing into the building insects such as termites which may abound in the log storage area.
It is an object of the present invention to provide a furnace capable of efficiently utilizing either solid or fluid fuel to effect the heating of a stream of air which may be circulated to rooms of a building other than the room containing said furnace. It is another object of the present invention to provide a fireplace furnace of the aforesaid nature capable of utilizing either a solid or fluid fuel in a manner to provide a continuous and controllable amount of heat. It is a further object to provide a furnace of the aforesaid nature which permits viewing of the combustion of solid fuel and has provision for receiving solid fuel from an access port located outside said building. It is still another object to provide a furnace of the aforesaid nature having a simplified construction which reduces manufacturing cost and facilitates maintenance. These objects and other objects and advantages of the invention will be apparent from the following description.